The present invention relates to wheelchair brakes for preventing unwanted rearward movement of a wheelchair during an occupant""s transitional ingress and egress, and more particularly to a wheelchair having a brake apparatus that automatically releases when a patient is properly seated.
Using a wheelchair enables patients suffering from various physical and mental disabilities to engage in some level of activity without experiencing the pain or limitations ordinarily placed upon them, and many patients who use wheelchairs are not permanently confined thereto. For these patients, the wheelchair is a convenient tool to facilitate mobility that is not possible otherwise. But often, getting in and out of the wheelchair can pose a problem for such users, in that the chair may roll backward unexpectedly as the patient transitions from standing to sitting, and vice versa. It is especially important that the wheelchair remains stationary during this period, since the natural motion associated with transitioning from sitting to standing, and vice versa, tends to transmit a rearward force on the wheelchair. Further, because only a minimal force is required to move the wheelchair backwards rather rapidly, the patient is extremely vulnerable to falling injuries.
In the past, various attempts to prevent such unwanted movement involved installing a braking mechanism on the wheelchair. In fact, most wheelchairs incorporate some type of brake which stabilizes the wheelchair in a stationary position by preventing rotation of the rear wheels. Conventional wheelchairs which are foldable for storage are invariably fitted with hand-operated brakes. These brakes engage the main drive wheels of the wheelchair, and are applied by the user, or an assistant, to stabilize the wheelchair before the user is seated. Once seated, the user releases the brakes by hand to again permit wheelchair mobility, and when the user wishes to leave the wheelchair, the brakes are re-applied. Brakes of this conventional type are adequate when the user is not seriously physically handicapped and when the user is in substantial control of his mental faculties. However, when the user is severely handicapped or otherwise unable to operate the hand brake, manual brakes are quite inadequate. An unaided user attempting to get into, or out of, a wheelchair which is not locked into a stationary position is faced with a difficult and dangerous task. Further, an unbraked wheelchair used as a temporary support to assist walking also presents a serious hazard to the user.
One of the most widely used devices for stopping and securing the wheelchair is a brake similar to that shown in U.S. Pat. No. 4,570,756 to Minnebraker et al., in which a lever arm is provided to urge a braking member into contact with the tread of the wheelchair tire. However, despite its popularity, this brake causes unnecessary wear to the tire tread, lacks substantial holding efficiency on sloped surfaces, and becomes almost unusable when the tire is wet. Since the device is only applied to one wheel, applying stopping action on both wheels of the wheelchair requires installation of two devices that must be engaged using two hands, which may not be an available option for a particular patient.
Similar wheelchair brakes are also disclosed in U.S. Pat. No. 3,529,700 to Marshall; U.S. Pat. No. 2,426,451 to Hammack; U.S. Pat. No. 4,384,732 to Wierwille; U.S. Pat. No. 4,852,697 to Kulik; and U.S. Pat. No. 4,350,227 to Knoche. All of these disclose braking devices for wheelchairs wherein braking pressure is applied directly to the tire rather than to the wheel rim.
Because of the above problems typically associated with prior wheelchair brakes, attempts have been made to provide an alternative brake system which automatically remains braked while the wheelchair is unoccupied, and which releases automatically under the weight of the user when properly seated.
For example, U.S. Pat. No. 4,623,043 to Babilas discloses an automatic wheelchair brake that automatically locks both wheels when a patient attempts to rise from the wheelchair. While seated, the patient can manually operate a three-way lever brake having a manual-locked, a manual-unlocked and an automatic position. If the patient attempts to rise while the brake lever is in the manually unlocked position, the lever automatically returns to the automatic position and both wheels still lock automatically. After the patient has exited, the wheelchair may only be moved by shifting the operating lever to the manual unlock position. However, the threat of rollback remains after the wheelchair is freely repositioned, especially if an unaided patient forgets to re-engage the manual-lock before sitting, or another unaware patient attempts to sit in the unbraked wheelchair. Thus, despite the automatic engagement feature, the manual nature of this brake is not generally desirable for seriously impaired patients.
Another wheelchair having an automatically engaging braking system is disclosed in U.S. Pat. No. 3,529,700 to Marshall, and uses chains or rod linkages connected between a set of rigid actuating bars attached to the seat panel to operate a pair of transverse brake levers which engage the main wheels. U.S. Pat. No. 4,320,818 to Knoche discloses a wheelchair brake assembly for use with a conventional foldable wheelchair which provides a pair of rearwardly extending brake arms connected to adjacent side frames underneath the seat. Each brake arm includes a transverse forward portion pivoted to the side frame and having a brake shoe biasing into engagement with a drive wheel. The rearward portion of each brake arm is provided with a post engageable by the wheelchair seat to pivot the brake shoe out of engagement with the wheel when the seat is depressed and moved downwardly by the weight of an occupant. The wheelchair side frames are connected by a tension spring to ensure that the brake is engaged when the wheelchair is unoccupied.
Yet another prior art wheelchair brake is the anti-rollback assembly of U.S. Pat. No. 6,092,824 to Ritchie. The one-way brake assembly is shown in FIGS. 1 and 2 as an example of a prior art wheelchair brake that automatically immobilizes the wheelchair against rearward movement when the occupant attempts to rise.
More specifically, FIG. 1 shows a wheelchair 1 having a frame 2 and an anti-rollback assembly. The anti-rollback assembly includes fastening devices 3A and 3B attached to opposing portions 2A and 2B of the frame 2 above the point where the opposing axles 4A and 4B intersect the frame 2. The fastening devices 3A and 3B include a large number of individual components as shown in FIG. 2, but the rotatable connection members 3a and 3b are most noteworthy for purposes of this discussion. A rigid crossbar 6A is rotatably attached to and interposed between the rotatable connection members 3a and 3b such that the rigid crossbar 6A transversely connects the fastening members 3A and 3B over the horizontal distance spanning between the two opposing sides 2A and 2B of the frame 2. The rigid cross bar 6A includes an arm 6B having a first portion 6a perpendicularly extending from the horizontal rigid crossbar 6A and joining with a second portion 6b at an elbow. The second portion 6b extends vertically upward from the elbow such that a third portion 6c is positioned under the wheelchair seat 7. A pair of brake arms 5A and 5B are rigidly attached to the rotatable connection members 3a and 3b and positioned to contact the rear wheels 20A and 20B such that the rear wheels are not moveable. When a patient sits on the wheelchair seat 7, the third portion 6c of the arm 6B is pressed downward, causing the rigid crossbar 6A to rotate in a rearward direction. The brake arms 5A and 5B lift upward in co-rotation with the rigid crossbar 6A and out of contact with the rear wheels 20A and 20B which are then freely moveable.
Another prior art wheelchair brake assembly is the wheelchair rollback stop of U.S. Pat. No. 6,347,688 to Hall et al. The device of Hall et al. includes a multi-part lever mechanism consisting of two levers that are attached to a wheelchair via an elongated (modified) axle bolt which acts as a fulcrum. The multi-part lever mechanism is activated (i.e., a plurality of posts with cane ends are pressed against the ground) when no patient is seated on the seat of the wheelchair, and deactivated when a patient""s weight depresses the wheelchair seat. The design of the multi-part lever mechanism involves a large number of individual components which must be assembled and adjusted to ensure that the rollback stop performs properly. For example, an unmodified wheelchair (i.e., a wheelchair having a standard axle bolt) must be modified, that is, the standard bolt must be removed and replaced with the elongated axle bolt mentioned above. In most cases, when the wheel axle bolt is removed from the wheelchair, the wheel requires substantial bracing to avoid complete removal, due to the fact that the removed axle bolt can no longer secure the wheel to the wheelchair. In that manner, to modify a wheelchair to accommodate the rollback stop of Hall et al., replacing an existing axle bolt is no small task. Once fitted with a suitable (i.e., elongated) axle bolt, the remainder of the multi-part lever mechanism must be attached and adjusted using a plurality of pins, springs, bolts, and set screws. Ultimately, installation is time consuming and complex.
Although automatic brakes, in general, offer advantages over manual brakes, room for improvement remains. Particularly, one problem is that the above mentioned automatic wheelchair brakes include a multitude of small parts which must be precisely adjusted to work in concert to accomplish the desired effect. Many people who are responsible for wheelchair maintenance are thus hesitant to tackle such complex installation of multi-component brakes.
Portability and storage of unoccupied wheelchairs are also hindered by complex automatic brake assemblies that typically brace the frame of the wheelchair transversely. Once automatic brakes with such rigid crossbars are installed, the brakes must be at least partially uninstalled to store, transport, or otherwise collapse the unoccupied wheelchair. Given the complex nature of the multiple-component assemblies, foldable storage and transport is not easily facilitated.
Another problem is that, in some brake designs, forward movement is restricted by the engaged brakes when the wheelchair is unoccupied, such that some type of a weight must first be placed on the empty seat to disengage the brakes and allow the desired forward motion, or a separate, complex mechanism must also be assembled to the wheelchair to disengage the brake. Further, positioning an unoccupied wheelchair by turning or moving it backward is not possible without placing a weight in the seat or otherwise mechanically disengaging the brakes.
Thus, it would be desirable to provide a wheelchair having a brake assembly that overcomes the drawbacks of the prior art. It would be particularly desirable to provide a cost effective wheelchair brake apparatus capable of automatic activation and release by an occupant, having few components to facilitate easy installation, having a nonrestrictive assembled structure to facilitate easy storage, and having a comfortable and efficient means of preventing unwanted motion of the wheelchair while users transition from a sitting position to a standing position, or vice versa.
It is an object of the present invention to overcome the drawbacks in the prior art, particularly to provide an automatically engageable and releasable wheelchair brake having few components to facilitate easy installation, having a nonrestrictive assembled structure to facilitate easy storage, and having a comfortable and efficient means of preventing unwanted motion, such as rollback, of the wheelchair while users transition from a sitting position to a standing position, or vice versa.
According to one embodiment of the present invention, an automatically engageable and releasable brake apparatus adaptable to be attached to a wheelchair is provided, including a connection mechanism adapted to be attached directly to a portion of the frame of the wheelchair proximate a rear wheel of the wheelchair, and a seat actuation member extending from a portion of the connection mechanism and adapted to be positioned substantially beneath the seat of the wheelchair. The brake apparatus also includes a shaft member extending from a first end thereof to an opposed second end thereof, positioned to extend substantially downwardly from a portion of the connection mechanism proximate the first end of the shaft member, and a friction member positioned proximate the second end of the shaft member and adapted to contact a ground surface on which the wheelchair is sitting.
According to the above embodiment of the present invention, occupational ingress, i.e., a user being seated, activates the seat actuation member to substantially contemporaneously move from a first position to a second position, which in turn causes the shaft member to move such that the friction member moves from a first position in substantial contact with the ground surface on which the wheelchair is located to a second position spaced a distance above the ground surface. Furthermore, occupational egress, i.e., when a user vacates the seat, activates the seat actuation member to move from the second position to the first position, which in turn causes the shaft member to move such that the friction member contemporaneously moves in relative concert from the second position spaced a distance above the ground surface to the first position in substantial contact with the ground surface. Thus, when the wheelchair is occupied, the friction member is in the second position, which allows the wheelchair to move both forward and backward under the user""s direction. When the wheelchair is vacated, the friction member is in the first position in contact with the ground surface, which stabilizes the wheelchair and prevents rearward motion.
The connection mechanism preferably includes at least one biasing member that urges the seat actuation member and the friction member toward their respective first positions. The length of the shaft member is preferably sufficient to allow the friction member to firmly contact the ground surface on which the wheel chair is sitting when the friction member is in the first position. Preferably, the connection mechanism is positioned on a vertical portion of the wheelchair frame approximately half the distance between the rear wheel axle and the base of the wheelchair seat.
The brake apparatus of the present invention is easy to install on a wheelchair using few tools and requires only minimal manual adjustments. In fact, very little manual positioning is needed to attach the connection mechanism, and both the shaft and the seat actuation members are easily positioned thereafter. In that manner, proper installation involves few parts, a single wrench, and as few as three bolts or Allen-head screws. The relative simplicity of the present invention thus eliminates the installation and maintenance problems commonly experienced in conjunction with the complex braking assemblies of the prior art.
The brake apparatus described above is assembled by first securing the connection mechanism to the wheelchair frame. As described above, the position of the connection mechanism is preferably about half the distance between the rear wheel axle and the base of the seat. The connection mechanism can be firmly attached in the appropriate position using a single nut and bolt (carriage bolt) assembly and tightened using a wrench. Next, the seat actuation member is assembled to the connection mechanism and positioned so that a portion of the seat actuation member raises the contour of the base of the unoccupied seat approximately 1 inch to 1.5 inches. The seat actuation member is then tightened in its position with respect to the connection mechanism using an appropriate fastener (e.g., Allen-head type set screw). It should be noted, however, that the position of the seat actuation member may need to be adjusted if an additional pad is placed in the wheelchair seat. In any event, the assembly should be tested after installation to ensure proper positioning of the seat actuation member before an actual patient is permitted to use the wheelchair. This is merely a common sense safety measure.
After the seat actuation member is positioned and secured, the shaft member is attached to the connection mechanism with the friction member oriented downwardly. The length of the shaft extending from the connection mechanism toward the friction member is adjusted so that the friction member firmly rests on the surface on which the wheel chair is sitting. The shaft member is held in the position by tightening a second fastener (e.g., an Allen-head type screw) proximate the connection mechanism. Upon completion of these three easy assembly steps, the wheel chair is properly equipped with the above embodiment of the brake apparatus of the present invention.
According to a second embodiment of the present invention, an automatically engageable and releasable brake apparatus adaptable to be attached to a wheelchair is provided, including a first connection mechanism adapted to be attached directly to a portion of the frame of the wheelchair proximate a rear wheel of the wheelchair, and a first seat actuation member extending from a portion of the first connection mechanism and adapted to be positioned substantially beneath the seat of the wheelchair. The brake apparatus also includes a first shaft member extending in a longitudinal direction from a first end to an opposed second end thereof, positioned to extend substantially downwardly in the longitudinal direction from a portion of the first connection mechanism proximate the first end of the first shaft member, and a first friction member positioned proximate the second end of the first shaft member and adapted to contact a ground surface on which the wheelchair is sitting. The brake apparatus further includes a second connection mechanism adapted to be attached directly to a portion of the frame of the wheelchair proximate the other rear wheel of the wheelchair, and a second seat actuation member extending from a portion of the second connection mechanism and adapted to be positioned substantially beneath the seat of the wheelchair. A second shaft member is also included, extending in a longitudinal direction from a first end to an opposed second end thereof, positioned to extend substantially downwardly in the longitudinal direction from a portion of the second connection mechanism proximate the first end of the second shaft member, and a second friction member positioned proximate the second end of the second shaft member and adapted to contact a ground surface on which the wheelchair is located.
According to the above second embodiment of the present invention, occupational ingress, as defined above, activates each of the first and second seat actuation members to move in relative concert from a first position to a second position, which in turn causes the first and second shaft members to contemporaneously move in relative concert such that the first and second friction members also move from a first position in substantial contact with the ground surface to a second position spaced a distance above the surface on which the wheelchair is located. Furthermore, occupational egress, as defined above, activates the first and second seat actuation members to move from the second position to the first position in contact with the ground surface, which in turn causes the first and second shaft members to substantially contemporaneously move in relative concert such that the friction members also move from the second position spaced a distance above the ground surface to the first position in substantial contact with the ground surface. That is, like in the above first embodiment, when the wheelchair is occupied, the friction members are in the second position, which allows the wheelchair to move both forward and backward under the user""s direction. When the wheelchair is vacated, the friction members are in the first position, which stabilizes the wheelchair and prevents rearward motion.
Preferably, the first and second shaft members are substantially parallel and oppose each other transversely across a substantially horizontal distance.
In a preferred mode of the present invention, an unoccupied wheelchair is braced against rearward movement near each of the main drive wheels without using a rigid crossbar for support. Additionally, the strength of the biasing members of the connection mechanism can be controlled, and independent yet coordinated movement of the parallel shaft members when the seat actuation members are activated is possible, which further eliminates the need for a rigid crossbar. In that manner, the fully assembled wheelchair brake apparatus of the present invention does not have to be removed to allow foldable storage of the wheelchair.
The present invention offers another advantage over prior art wheelchair brakes in that an unoccupied wheelchair equipped with the braking apparatus of the present invention can still be moved forward and turnably positioned without significant resistance or inhibition. That is, the engaged friction members slightly disengage to drag behind the wheelchair without causing any substantial restriction to the directed forward and turning motion movement.
Moreover, according to another embodiment of the present invention, the shaft member is equipped with a threaded knob proximate the connection mechanism, which can be used to manually loosen the shaft member and raise the friction member above the ground surface. This minor adjustment is performed quickly and easily, allows unimpeded forward and backward transportation of the wheelchair and helps reduce wear of the friction members during transportation of the unoccupied wheelchair.
According to a third embodiment of the present invention, an automatically engageable and releasable brake apparatus adaptable to be attached to a wheelchair is provided, including a first connection mechanism adapted to be attached directly to a portion of the frame of the wheelchair proximate a rear wheel of the wheelchair, and a second connection mechanism adapted to be attached directly to a portion of the frame of the wheelchair proximate the other rear wheel of the wheelchair and opposite the first connection mechanism. The brake apparatus also includes a seat actuation member having a first portion extending from a first portion of the first connection mechanism, a second portion extending from a second portion of the second connection mechanism, and a third portion substantially connecting the first and the second portions of the seat actuation member. At least the third portion of the seat actuation member is adapted to be positioned substantially beneath the seat of the wheelchair. A first shaft member is included, extending in a longitudinal direction from a first end thereof to an opposed second end thereof and positioned to extend substantially downwardly in the longitudinal direction from a second portion of the first connection mechanism proximate the first end of the first shaft member, and a first friction member positioned proximate the second end of the first shaft member and adapted to contact a ground surface on which the wheelchair is sitting. A second shaft member is further included, extending in a longitudinal direction from a first end thereof to an opposed second end thereof and positioned to extend substantially downwardly in the longitudinal direction from a second portion of the second connection mechanism proximate the first end of the second shaft member, and a second friction member positioned proximate the second end of the second shaft member and adapted to contact a ground surface on which the wheelchair is sitting.
According to the above third embodiment of the present invention, occupational ingress activates at least the third portion of the seat actuation member to move from a first position to a second position, which in turn causes the first and second shaft members to move such that the first and second friction members also substantially contemporaneously move in relative concert from a first position in substantial contact with the surface on which the wheelchair is located to a second position spaced a distance above the ground surface. Furthermore, occupational egress, as defined above, activates at least the third portion of the seat actuation member to move from the second position to the first position, which in turn causes the first and second shaft members to move such that the first and second friction members also substantially contemporaneously move from the second position spaced a distance above the ground to the first position in substantial contact with the ground surface. Thus, as in the previous embodiments, when the wheelchair is occupied, the friction members are in the second position, which allows the wheelchair to move both forward and backward under the user""s direction. And, when the wheelchair is vacated, the friction members are in the first position, which stabilizes the wheelchair and prevents rearward motion.
Preferably, the first and second portions of the seat actuation member are connected to the third portion to facilitate collapsible storage of the wheelchair. Any type of connector that allows the first and second portions to move in conjunction with the third portion when the wheelchair is folded can be used, so long as the connectors do not prevent the three portions of the seat actuation member from operating as a substantially rigid unit when the third portion of the seat actuation member is moved from the first position to the second position during occupational ingress.
As described above, various embodiments of the present invention are quickly and easily installed on many different types of wheelchairs using a minimal number of tools, and installations require only minor manual adjustments to ensure proper performance during use. Further, because a rigid transverse brace bar is not required, the brake apparatus of the present invention does not need to be disassembled in order to fold, store or transport the wheelchair. Moreover, the structural configuration of the brake apparatus of the present invention allows an unoccupied wheelchair to be pushed forward or turned, whereas such motion has been heretofore restricted by many of the prior art brake assemblies.